Background of Lens Development Plan

We went ahead with the idea of making a lens that helps customers to explore new photographic expressions with advanced function and performance. Also, we wanted to deliver a maximum shooting magnification of 1.4, SA control ring that can freely adjust bokeh expression, powerful image stabilization to broaden photos and video shooting possibility. We are convinced that these key features will stimulate the creativity of the photographer.

Reason for Setting the Maximum Magnification to 1.4

The main purpose of using a macro lens is to take macro shots that are close to the subject, so we thought the biggest appeal of this lens would be to exceed the maximum shooting magnification of 1.0x which has been the normal. With 1.4 magnification, you should be able to produce photos and videos that are different from previous 1.0x macro lenses. And now 1.4 comes with higher image quality. We thought that would be of great value to our customers.

Scenes Where Macro Photography is Effective

There is a wide range of subjects for macro photography, such as flowers, small creatures and small objects. For the photo shoot workflow such as zoom in, zoom out, focus, expose and frame the subject and then releases the shutter, there are times when you want a little more magnification. In such cases, it’s good to have room up to 1.4 magnification. Also, this lens's powerful IS reduces camera shake, so you can focus on shooting with peace of mind.

Advantages of Capturing Subjects at 1.4 Magnification

Modern digital cameras have high pixels, so you can often crop the original shot to the equivalent of 1.4 with good image quality. But with macro lens, you can focus more on subject and composition looking through the viewfinder. I think that kind of uplifted feeling will lead to joy of shooting experience and a satisfying result.

Effects of 1.4 Macro Photography

With this macro lens, the maximum shooting magnification is 1.4, which is more than usual macro lens. The higher the shooting magnification, the shallower the depth of field. With this high magnification and shallow depth of field, you can discover new subjects and expressions. Instead of looking for the subject with your eyes, you can enjoy looking for the subject through the lens. You might be surprised about the beauty hidden in the detail of the subject in front of you. I think there are times when something you've never pointed a lens at before becomes a wonderful subject.

Expanded Range of Expressions Over Conventional Macro Lenses

I think this lens can represent an abstract world like never before. Of course, it can also provide sharp and realistic expressions. This is a lens with a wide range of expressions. It's even more fun to use the SA control ring.

Newly Featured SA Control Ring

This function adjusts the bokeh expression by changing the spherical aberration (SA). By rotating the SA control ring on the lens barrel in the plus or minus direction, you can freely soften or harden the front or back blur depending on the shooting expression. Depending on the amount of rotation, the softness of the image in focus can be adjusted, making this a great feature not only for macro shots of flowers, but also for portraits.

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Reasons Why Macro Lenses are Needed

For example, when you want to make a bigger image of a small flower, you step forward to get closer, right? However, most common lenses don’t focus well even if you move closer to get a bigger picture. Furthermore, even if the camera is in focus, the closer you get, the worse the image quality becomes normally. Macro lenses are designed to solve such problems by providing good focus even when you are close to the subject.

Macro Lens Design

The macro lens design is similar to the zoom lens design. The macro lens moves each lens in a large way like a zoom lens to increase the shooting magnification. But unlike the zooming move by manually, autofocus, which requires speed and precision, requires special design. Therefore, macro lenses that support autofocus are designed with a lot of technology to achieve quickness and accuracy, including not only the weight and trajectory of the moving lens but also how to hold and control the lens.

Advantages of 1.4 Magnification

We aimed for 1.4 for this lens to enable confident macro photography and a wider expression. In case of a 1.0x magnification lens, it is easy to lose focus if the subject comes even slightly closer from the position. However, by using a macro lens that can shoot up to 1.4 magnification, there is more room in the shooting distance, and even if the subject suddenly gets close, it will be in focus and you will be able to take pictures with confidence. Furthermore, when shot at equal or higher magnification, it can depict a beautiful world that is completely different from what your eyes see. I would like you to experience the beautiful macro world through this lens.

Realization of AF and 1.4 Magnification

The large aperture and short back focus enabled maximizing the range of motion of the focus lens. The optics of a typical macro lens have been refined over time, and focus type, IS type and aperture position are fixed to some extent. However, it was essential to break away from the existing types in order to achieve a 1.4 this time. Unlike conventional macro lenses, this lens achieves 1.4 by placing the IS or aperture in the front, separating it from the focus, and moving the focus lens to the very edge of the mount.

Design Ingenuity

First of all, it's important to always think from the ground up and not get caught up in common sense. I think it will be difficult to break away from existing types and create new value in any field. In fact, the design of this macro lens started with a single convex lens, rather than a design based on existing lenses, which led us to this arrangement. If you compare the cross section of this lens to other macro lenses, you may see that it has a completely different configuration.

Delivering High-Quality Images

Special lenses are usually used to reduce the occurrence of aberrations, but this lens does not use that special lens to reduce aberrations. This was made possible by the use of a concave lens in the foreground, which gently accepts light rays from close subjects and gradually bends the light to reduce the occurrence of spherical aberration. Then I added a convex lens and corrected chromatic aberration.

Differences Between Equal Magnification and 1.4

As the shooting magnification increases, the range of focus becomes very narrow, and the blurred range increases, allowing for more mystical depictions. However, a slight camera shake can cause the camera to go out of focus, making it difficult to focus on the area you want to focus on. Also, the fact that the subject appears larger means that camera shake has a greater impact than usual. So, when you’re shooting at 1.4, you need precise autofocus and powerful image stabilization.

Powerful Image Stabilization

We designed the aberration variation to be smaller when the image stabilization lens is moved. In addition, it cooperates with the camera's in-body image stabilization for even more powerful image stabilization.

Design of Autofocus

In order to achieve 1.4 magnification, we had to move multiple lenses widely. This lens is equipped with a Canon proprietary ultrasonic motor called “Nano USM” which achieves high-speed, high-precision autofocus.

Photographic Genres that this Lens is Well Suited For

We designed it to achieve high image quality not only in macro photography, but also in all shooting areas, including landscapes and portraits.

Movie Shooting

This macro lens is equipped with Nano USM, so you can enjoy comfortable video shooting with quiet and quick autofocus. In addition, when shooting video, you might be concerned about focus breathing, which is the angle of view change during focus. By adopting a new focus type for this lens, the focus breathing is mitigated.

Development of SA Control

The idea to control the spherical aberration called “SA” was inspired by the fact that the Nano USM can freely change the focus trajectory. By precisely controlling the aberration, which only made the image quality worse, we were able to increase the freedom of expression, such as softening the bokeh or making it harder.

How to Enjoy this Lens

Process of Downsizing

Canon’s efforts to develop these lenses began with the choice of the most appropriate optical design. Lens optical systems can be divided into two types: “fixed-length” and “variable-length”. The latter alters the overall length of the lens in order to achieve focus. This design has advantages for miniaturization, since it can make use of the unique short-back-focus characteristics of mirrorless cameras. On the other hand, the design does compromise some of the flexibility and ease of use that was typical of EF-era lenses.

Despite some reservations about this issue, Canon decided that users may be willing to compromise some degree of usability in return for better quality and a broader range of potential photographic expression. It is hoped that this will encourage existing Canon customers to adopt the new EOS R system.

F4 and F2.8 Models

We actually considered adopting a fixed-length design for the F4 lens. This would differentiate it from the F2.8 design and also make it extender-compatible. However, we soon determined that this would make the F4 lens too bulky for most users. Since the basic structure of an F4 lens allows it to be made smaller than the F2.8 lens, we chose to take full advantage of this merit, adopting the same optical structure for the F4 lens as the F2.8 lens, and making it as small as possible.

Extender Not Supported

Adopting a new design for the RF series was a bit of a dilemma. We wanted users to be excited about the future potential of the EOS R system, but we are also aware that existing users may want lenses to be compatible with their extender. Unfortunately, when we tried to simulate a new lens design that would support an extender, we found that the overall length of the lens did not contract much at the wide-angle end. Therefore, it was not as compact as we had expected, especially compared to EF-era lenses.

While the EF70-200mm f/2.8L IS III USM was well received, some users complained that it was too bulky. In order to maximize the advantages of the interchangeable-lens system, when designing the RF70-200mm F2.8 L IS USM, we made the difficult decision not to make it compatible with extenders. This allowed us to reduce overall length dramatically — by about 25% compared to EF lenses.

When I first saw the F2.8 lens prototype, I was amazed at how small it could be. But the F4 lens is no less impressive. It has been miniaturized to about the same size as a standard F4 zoom lens.
The torque required to adjust the overall length of the zoom lens is greater, since the structure requires lens elements to be moved outward and inward. This makes the zoom ring harder to turn. We took great pains to ensure that the zoom ring would be light and easy to turn. In short, when we designed these lenses, we had to address a multitude of difficult issues in terms of miniaturization and extender compatibility.

Reduced Weight

Naturally it is important for lenses to be lightweight, but I believe it is also important to have a good weight balance between the lens and the camera body. While taking steps to miniaturize RF lenses, Canon is also making EOS R cameras smaller and lighter.

We take into account how balance and size will be affected when the lens is attached to cameras such as the EOS R5 and R6. I think this is going to make things much easier for photographers who have to carry a camera around for hours at a time. I welcome feedback from people who use the new EOS system.

Optical Design

The F2.8 and F4 lenses are based on the same general technologies. I’d like to discuss the optical design of these lenses in a bit more detail. In the past, zoom lenses in the 70-200mm range used a fixed-length type design. However, for the RF lens series Canon adopted a new optical system that uses a method called “multi-group zooming”, in which each lens group has a function that is not restricted by the old roles of variable magnification, focus, and aberration correction.

This lens was the first to adopt a drive motor to control the floating group. A floating group is a group of lens elements used primarily to cancel out aberrations. We set out to improve the basic performance of the lens by controlling the floating group with a motor, so that no matter the zoom position or focus distance, the lens captures images with beautiful quality and minimal aberration.

The use of this electronic floating system also helps to shorten the minimum focusing distance — from 1.2m with the f/2.8 EF lens to 0.7m with the f/2.8 RF lens. It is possible to design a lens that allows you to get closer to a subject at the wide-end setting, but users want to get closer at the telephoto end, too!

For this reason, the minimum focus distance of the f/4 lens has been reduced to 60cm. I think it is quite exciting to use this downsized 70-200mm lens to take pictures of a subject that is close enough to reach out and touch.

AF Performance

We faced some difficulties in developing the electronic floating system. For example, if a delay occurs in adjusting the position, due to motor control, it could cause substantial aberration and inaccurate focus. We modified the control system in various ways to try to prevent this from occurring, but it was difficult to get it right the first time.

In fact, we encountered quite a few problems when we were field-testing the first prototype. It was difficult to get the camera to focus, and only after a lot of tinkering and many late-night discussions were we finally able to improve the performance to the point where it delivers photo results that we could be satisfied with.

It was extremely difficult to design a control system that could adjust the focal lens group to bring the subject into focus, while simultaneously controlling the floating group.

A good AF system needs to adjust the camera lens swiftly, to focus on the subject in a split second. However, with the new lens design, the positions of two separate lens groups have to be controlled simultaneously, with a micron-level degree of precision. Canon’s new control system accurately calculates not only the final stop position; it also the adjusts and compensates the position of the two lenses at every given moment during the focal adjustment, on a micron-by-micron basis, to avoid any deviation from the perfect focal position.

If this exact positioning is not maintained, aberration can occur during the focusing process, so a moving subject would not remain in focus. It took a lot of effort and repeated trial-and-error testing to finally produce lenses that can perfectly focus on a subject at high speed.

The result is something that photographers have long awaited — a camera that can focus on moving subjects and capture images with the same image quality as those of stationary subjects.

Reliability

As explained earlier, we adopted a type of zoom lens that changes in overall length as focus is adjusted. Of course, a zoom lens with a front that extends and contracts can be problematic, since the lens tip may accidentally bump into something as the lens focuses.

Therefore, we decided to employ six cam followers (parts that hold the movable lens barrel in place), to shift the front element on the barrel of the F4 lens, and twelve cam followers on the F2.8 lens. Both of these figures are double the normal number of cam followers to hold the lens barrel. After repeated in-house tests, we are proud to introduce these lenses as “genuine Canon 70-200mm lenses”.

High Image Quality

The image quality provided by these lenses has improved greatly. Not only have we suppressed spherical aberration at the center of the image; the peripheral image quality has also been improved by suppressing chromatic aberration and image curvature. This is partly thanks to the electronic floating system, as explained earlier. However, the choice of a variable-length optical design has also eliminated the need for an unreasonably long focal length for wide-angle settings, allowing for a more natural design.

The RF70-200mm F2.8 L IS USM is very good at resisting underexposure in backlit situations. For example, when taking photos of an approaching train, the camera is able to take clear photos of the entire train even in situations where the headlights of the train create a lighting dilemma. The development of new glass coatings and sophisticated simulation technology also contribute to this capability.

Other optical elements have evolved over the years. For example, the RF70-200mm F2.8 L IS USM was the first Canon camera to feature an aspherical UD lens. Although it is difficult to explain the technical reasons why, this helps to shorten the overall length of lenses by a few millimeters. Furthermore, the number of lens elements has been decreased, thus greatly reducing weight.

Image Stabilizer (IS)

Another major benefit of RF series lenses is their support for Coordinated Control IS with the camera’s in-body IS. The F4 lens is not as bright as the F2.8 lens, so the user may need to reduce shutter speed in some situations. When taking handheld photos at night, for example, a slow shutter speed may adversely affect photo quality.

However, Coordinated Control IS can achieve camera-shake blur correction as effective as an increase in shutter speed of up to 7.5 stops, making handheld photography much more practical. These and other technological innovations put the RF series of lenses in a paradigm unlike the EF era. I expect that Canon lens users will need to consider new factors when choosing an RF series lens.

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